Our goal is to understand the formation of molecular hydrogen in the interstellar medium (ISM). To this end we use an experimental setup to investigate the roles played by the cosmic dust (modeled by an amorphous silicate surface) and the surrounding ISM gas (modeled as a beam of deuterium atoms) on D2formation. These experiments are performed in ultra-high vacuum conditions. We use a QMS (Quadrupole Mass Spectrometer) to monitor the dynamical coverage and sticking of D atoms and D2 molecules on dust, while a REMPI-TOF (Resonantly Enhanced Multi-photon Ionization – Time of Flight) spectrometer monitors the newly formed D2 molecules, assuming a formation rovibrational distribution peaking at v” = 4, J” = 2. These experiments confirm that a silicate pre-covered with D2 molecules enhances the formation of new D2 molecules.